It’s many years since I saw it but, IIRC, Pretty Baby does at least pay some attention to the main character’s lack of choices and acknowledges she is forced into prostitution (albeit a very sanitised version). It would not have been that shocking if BS had been a young adult when filming it. I’ve never seen Blue Lagoon, but my impression is that is straight-up soft porn.
With both though, it’s unbelievable - even for the 70s - that no one involved in the production thought, “Hold on, this is a child”.
Poor Brooke. She is incredibly strong to have survived this.